An often desired objective and, in some instances, a requirement of a transmitting and/or receiving antenna system, is the ability of the system to scan one frequency without affecting another frequency that the system may be transmitting or receiving. A conventional approach to meet this objective has involved the use of often complicated, special purpose, mechanically displaced antenna feed or dielectric lens arrangements, through which control of the desired scanning operation is exclusively conducted. Unfortunately, such systems may be both complex and costly, and their operations may differ depending upon the type of system involved. For example, for a dual apex/cassegrain system, conventional practice has been to separately scan each feed; on the other hand, a dichroic scanner operates for each feed simultaneously.